Iron Absorption From a Nutritional Iron Supplement

November 2, 2026 updated by: Nicole Stoffel, ETH Zurich

Conventional oral iron supplements often cause gastrointestinal side effects and are limited by poor bioavailability, leaving unabsorbed iron to reach the colon. Hydrocolloid-based hydrogel matrix formulations designed for gradual iron release present a promising approach to improve iron absorption. This study evaluates fractional iron absorption (FIA) from three low-dose hydrogel formulations containing ferrous fumarate compared with ferrous fumarate without a hydrogel matrix. Test products will be administered with water, with and without a standardized breakfast. All formulations will be intrinsically labelled with stable iron isotopes ( 57Fe or 54Fe), and FIA will be determined 14 days after administration based on erythrocyte iron incorporation. In this randomized, within-subject corssover study conducted in non-anemic, iron-depleted women, each participant will receive all test conditions and serve as her own control.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
22

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Switzerland
    • Canton of Zurich
      • Zurich, Canton of Zurich, Switzerland, 8006

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 45 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

Female

Description

Inclusion Criteria:

  • Female aged 18 to 45 years
  • Plasma ferritin <30 µg/L
  • Body mass index (BMI) 18.5 kg/m2 - 24.9 kg/m2.
  • Body weight <65 kg.
  • Signed informed consent
  • Sufficient command of English (mother tongue or B2 level)

Exclusion Criteria:

  • Anemia, defined as hemoglobin (Hb) <120 g/L (<12.0 g/dL).
  • Elevated systemic inflammatory markers (C-reactive protein >5.0 mg/L).
  • Chronic digestive, renal and/or metabolic diseases
  • Chronic medications (except for contraceptives)
  • Use of vitamin, mineral, or pre-/Pprobiotic supplements in the 2 weeks before or during the study
  • Blood transfusion, blood donation or significant blood loss (>400ml) over the past 4 months
  • Difficulty with blood withdrawal
  • Pregnancy (tested in serum/urine) or intention to become pregnant during the course of the study
  • Lactation
  • Previous participation in a study using stable isotopes or participation in any clinical study within the last 30 days
  • Participants who cannot be expected to comply with the study protocol (e.g. not available on certain study appointments)
  • Inability to understand the information sheet and the informed consent form due to cognitive or language reasons
  • Smoking (>1 cigarette/week)
  • Vegan diet (the standardized breakfast contains plain whole milk yogurt and butter)

Special exclusion criteria for participants in the MRI imaging sub-study (n=9):

  • Presence of a heart pacemaker, neurostimulator, or any other active implanted electronic device.
  • Use of a hearing aid that cannot be safely removed for the MRI examination.
  • Use of removable dentures that cannot be safely removed for the MRI examination.
  • History of surgery on the head or heart involving implanted material that is not confirmed MRI-safe.
  • Presence of metallic objects in the body (e.g. implants, magnets, metal splinters, gunshot fragments, tattoos, piercings, or surgical clips) that are not confirmed MRI-safe.
  • History of metal splinter injury (e.g. ocular foreign body) or occupational exposure associated with increased risk of retained metal fragments.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Other
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: FeHydro-A with breakfast (Condition 1)

FeHydro-A with sodium ascorbate, consumed with a standardized breakfast
Dietary supplement: Iron-Enriched Hydrogel Supplement (A with breakfast)

FeHydro-A (20 mg elemental iron as ferrous fumarate embedded in hydrogel matrix; labeled with 57Fe or 54Fe) + Standardized Breakfast

Other Names:
  • FeHydroA
Experimental: FeHydro-B with breakfast (Condition 2)

FeHydro-B without sodium ascorbate, consumed with a standardized breakfast
Dietary supplement: Iron-Enriched Hydrogel Supplement (B with breakfast)

FeHydro-B (20 mg elemental iron as ferrous fumarate embedded in hydrogel matrix; labeled with 57Fe or 54Fe) + Standardized Breakfast

Other Names:
  • FeHydro B
Experimental: FeHydro-A without breakfast (Condition 3)

FeHydro-A with sodium ascorbate, consumed without breakfast
Dietary supplement: Iron-Enriched Hydrogel Supplement (A without breakfast)

FeHydro-A (20 mg elemental iron as ferrous fumarate embedded in hydrogel matrix; labeled with 57Fe or 54Fe) + 300 mL Water
Experimental: FeHydro-B without breakfast (Condition 4)

FeHydro-B without sodium ascorbate, consumed without breakfast
Dietary supplement: Iron-Enriched Hydrogel Supplement (B without breakfast)

FeHydro-B (20 mg elemental iron as ferrous fumarate embedded in hydrogel matrix; labeled with 57Fe or 54Fe) + 300 mL Water
Experimental: FeHydro-C with breakfast (Condition 5)

FeHydro-C with sodium ascorbate and gum arabic, consumed with a standardized breakfast
Dietary supplement: Iron-Enriched Hydrogel Supplement (C with breakfast)

FeHydro-C (20 mg elemental iron as ferrous fumarate embedded in hydrogel matrix; labeled with 57Fe or 54Fe) + Standardized Breakfast
Active Comparator: Control with breakfast (Condition 6)

Control ferrous fumarate, consumed with a standardized breakfast
Dietary supplement: Control (FeFum, with breakfast)

Control (20 mg elemental iron as ferrous fumarate without hydrogel matrix, in gelatin capsule; labeled with 57Fe or 54Fe) + Standardized Breakfast
Active Comparator: Control without breakfast (Condition 7)

Control ferrous fumarate, consumed without breakfast
Dietary supplement: Control (FeFum, without breakfast)

Control (20 mg elemental iron as ferrous fumarate without hydrogel matrix, in gelatin capsule; labeled with 57Fe or 54Fe) + 300 mL Water

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Fractional Iron Absorption
Time Frame: 14 days after administration of each labelled test condition

Fractional iron absorption will be calculated based on the shift of the iron isotope ratios in red blood cells
14 days after administration of each labelled test condition

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
ETH Zurich

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Swiss Distance University of Applied Sciences

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 1, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
February 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 2, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 2, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 6, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
November 6, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 2, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • IRONH

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data (IPD) will not be made publicly available to protect participant privacy and maintain confidentiality regarding proprietary formulation data. De-identified, aggregated study results and primary outcome data will be published in peer-reviewed scientific journals and made available via public study registries upon completion of the trial.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Cookie Settings

We use cookies to ensure that we give you the best experience on our website. For more details carefully read our Privacy and Cookies Policy. ...>>>You can change your preferences or withdraw your consent at any time by deleting the cookies from your website or computer as described in the policy. Please accept it and choose your preferences by ticking the corresponding boxes in the "Manage Settings" section below. Please carefully read our Terms of Service before you proceed with using any part of this website.
«Manage Settings